1. Field of the Invention
This invention relates to thoroughfare crossing guards, more particularly to a crossing guard for use at bridge and railroad crossings.
2. Prior Art
Many devices have been used to prevent motorists on a thoroughfare from crossing railroad tracks or even raised bridges. Many of these devices included a cross arm connected to an operator that raises and lowers the arm. While practical, these devices can be ineffective because many motorists simply drive around or through the arm. If a motorist is not paying attention he can simply drive through the arm and into the way of an oncoming train or other danger because the arms are constructed from wood or plastic. Use of stronger materials such as steel can be impractical because of the added weight and the concerns about the safety of drivers who crash into the arm.
In the past, attempts have been made to use arms having cables attached thereto or cables positioned within a hollow arm member extending between the sides of the roadway. In U.S. Pat. No. 4,989,835 to Hirsh, a security gate for preventing terrorists from proceeding past a designated point on a thoroughfare was disclosed. Hirsh discloses an operator with an arm connected thereto. A pair of posts is located on either side of the thoroughfare. A pipe is connected at either end of the arm with cables extending between the pipes and along the arm. When the arm is lowered, the pipes fit exterior of each pair of posts with the posts acting to restrain the cables if a vehicle impacts the arm, thus restraining the vehicle. Hirsh discloses that the cables should be placed between twenty-seven and thirty-five inches above the ground.
While the prior art discloses means for stopping vehicles, the prior art devices have several drawbacks. First, because the cables are not joined together, the upper cable(s) can ride up and over the hood of a vehicle and cut through the roof, thereby injuring the passengers. The height of the cables disclosed in Hirsh emphasizes this danger. Second, Hirsh does not disclose additional energy absorbing material that will aid in stopping the vehicle before the cables begin restraining the vehicle. Third, none of the prior art devices discloses the use of ties to hold the cables in position relative to one another so that the cables remain somewhat in position relative to each other. Finally, the prior art fails to disclose the locking mechanisms used herein to lock the arm and cable ends in place.